The present invention relates generally to the rotor element of fluid control valves or a rotor used with an actuator. In particular, it relates to the rotor element of electrically actuated valves of the type utilized in internal combustion engines as governors to throttle the flow of fuel so as to moderate fuel pressure.
In internal combustion engines, and in manufacturing applications such as chemical processing, it is often necessary to control fluids flowing through lines of 0.98 to 0.789 cm in diameter. The fluids traversing these lines flow at a relatively fast rate. Due to the nature of the end process of the fluid, it is sometimes necessary to change the fluid flow rate, often from full on to full off, at rapid rates, over a sustained period of time.
Valves have been designed which are able to control fluid flow, by opening and closing their orifices, and which are able to withstand the wear of vigorous use. One such valve is disclosed in U.S. Pat. No. 4,339,737 to Meyers and Glynn. This valve comprises a rotor having a magnetically actuated rotor body housed in a stator with a coil means, and a hollow rotor stem housed in a valve sleeve. The rotor body-rotor stem is a one piece unit. The rotor stem and the valve sleeve each have a pair of symmetrical ports, which when aligned allow unrestricted fluid flow. The valve is inserted into the body of a fuel pump so that the valve sleeve and rotor stem are located in the cavity of the pump. Within the cavity the fuel is under pressure, so that when the ports on the rotor stem and valve sleeve are aligned, fuel is forced through the rotor stem and out the valve sleeve through lines connected thereto. Energizing the stator coil attracts the magnetic poles on the rotor, causing it to turn. The movement of the rotor causes the orifice formed by the two sets of ports to change size, thus controlling the flow rate of fluid flowing through the valve. Through the use of magnets, guides, and springs, the rotor turns at a constant rate, turns only through a defined arc, and returns to its original position when the stator is deenergized. An additional feature of this device is a rotor stem extending below the valve ports. This rotor stem, resting in the valve sleeve, serves to stabilize the rotor as it turns.
One disadvantage of the valves of this type is that they are affected by stress from the liquid in the pump cavity. The liquid in the pump cavity is under changing pressure that subjects the valve sleeve wih the rotor stem therein to lateral forces, causing the valve sleeve to bend. The bending of the valve sleeve may cause the rotor stem to bend, forcing it out of alignment. Such bending may also serve to reduce the lifespan of the valve.
One device which attempts to overcome this disadvantage is disclosed in U.S. application Ser. No. 729,917 which has the same assignee as the present invention. Unlike the device of U.S. Pat. No. 4,339,737, the rotor body-rotor stem of Ser. No. 729,917 is of a two-piece construction, such that relative pivoting motion between the rotor body and rotor stem is possible. In this manner some of the stresses on the rotor are alleviated.
While this design alleviates, to some extent, the problems caused by the liquid under pressure associated with the single piece rotor body-rotor stem design, it does not allow optimum pivoting motion at the flexible joint of the rotor stem.
Thus it is an object of this invention to provide a rotor of such design so as to freely flex within the valve sleeve. This design insures that the complementary parts will stay aligned, thereby maintaining the efficiency of the valve. A further advantage of this design is that wear on the device will be reduced thus increasing the useful life of the valve.
In systems known to the applicant, the manufacture of such valves is extremely difficult. This is in part because the various valve elements are of relatively small size; stators are 1.969-3.937 cm high, and at their smallest, may be 0.787-1.575 cm across. The rotor stem required to fit inside the sleeve is, of course, smaller; it may be 1.575-2.756 cm high and at its smallest 0.098-.591 cm in diameter. Because the various valve parts are required to be precisely aligned, the parts must be assembled precisely. As a result, the cost of manufacturing these valves is relatively high.
Hence, it is an additional objective of this invention to provide a valve rotor of such design that it can be inserted into the valve sleeve without precise alignment and yet will function properly.